Resistance welding of railroad rails is often used to join two rail sections together as a railway is built or repaired. This type of welding is commonly referred to as “flash butt welding.” During flash butt welding, the two rails ends to be joined are first heated and then forged together, expelling liquid metal and oxides from the weld joint. The forged joint is sheared to remove the flash, which is solidified material that was forced out of the joint during forging.
A typical flash butt weld requires cleaning the rail ends by flashing off oxides and impurities, followed by forging the rail ends together. The flashing step involves bringing the rail ends into contact and resistively heating and removing the protrusions that come into contact, so that the end result, prior to forging, is a set of rail end faces that are macroscopically planar and parallel to one another, and whose planes are substantially perpendicular to the track axis within some acceptable degree of variance. In this way, the resulting forge joint may be made uniform and strong across the entire rail cross-section.
However, in practice, when rail ends are cut to the appropriate length, the rail end face may be nonperpendicular to the rail axis and, more importantly, may be nonparallel to the mating rail end face. Thus, the flashing step also needs to be preceded by a “burn-off” step to remove sufficient material from one or both faces so as to render the mating faces mutually parallel. In such cases, it is important for the operator to ensure that a sufficient amount of material is removed without allowing excess burn-off and rail truncation. Traditionally, the burn-off has been difficult to perform with precision, and thus, the squaring of rail ends has either taken excessive operator supervision, with the attendant risks of human error, or has been neglected entirely.
When considering this background section, the disclosure and claims herein should not be limited by the deficiencies of the prior art. In other words, the solution of those deficiencies, while desirable, is not a critical limitation of any claim except where otherwise expressly noted in that claim. Moreover, while this background section is presented as a convenience to the reader who may not be of skill in this art, it will be appreciated that this section is too brief to attempt to accurately and completely survey the prior art. The preceding background description is thus a simplified and anecdotal narrative and is not intended to replace printed references in the art. To the extent an inconsistency or omission between the demonstrated state of the printed art and the foregoing narrative exists, the foregoing narrative is not intended to cure such inconsistency or omission. Rather, applicants would defer to the demonstrated state of the printed art.